A radio access network (RAN) configuration has been changed such that various types of small cells such as a pico cell, a femto cell, etc. interact with a macro cell. The RAN configuration refers to a heterogeneous cell configuration or a hierarchical cell configuration in which small cells for low power/near field communication coexist in addition to an existing macro cell-based homogeneous network.
It is inefficient to additionally install a macro cell eNB in a complex urban environment like in a conventional art. This is because system throughput enhancement is not high compared with increase in costs and complexity for additional installment of macro cells due to shadow areas of a communication environment. Accordingly, in a new heterogeneous cell structure, a plurality of small cells coexists in a macro cell and serves corresponding UEs by resource allocation based on cell coordination. The heterogeneous cell structure is used to enhance quality of experience (QoE) by providing a high data transmission rate to a last user.
In small cell enhancements for E-UTRA and E-UTRAN study item (SI) as one of 3rd generation partnership project (3GPP) standard scopes, research has been ongoing into enhancement of indoor/outdoor scenarios using low power nodes, and the scenarios is described in 3GPP TR 36.932. In small cell enhancements for E-UTRA and E-UTRAN SI, research has been conduced to draw advantages of concept of dual connectivity to small cell layers and a macro cell layer in which a user uses the same or different carriers.